The major objectives of this Sexually Transmitted Infections Co-operative Research Center (STI-CRC) entitled Innate and Adaptive Immunity in Experimental and Human Gonococcal Infection in Women are directed to providing a diverse and comprehensive understanding of the innate and adaptive immune mechanisms associated with gonococcal infection. We will emphasize basic host responses and innate immune mechanisms in infection with Neisseria gonorrhoeae with the immediate aim of improving understanding of gonococcal immunology and pathogenesis and a longer term goal to gain insights that will direct efforts to facilitate the prevention of gonococcal infections in humans, particularly women. We will use a promising animal model to examine these mechanisms and separately employ a generalized translational approach that will emphasize the links between immunobiology and clinical epidemiology to assess the potential of vaccine candidates in humans, which will then be investigated in the context of the humanized mouse model of infection. Five research projects and four service cores are proposed. In the first project (Douglas T Golenbock, MD, PL), we will address a basic and fundamental question in lipopolysaccharide (LPS, called lipooligosaccharide [LOS] in the case of N. gonorrhoeae) biology to understand the binding of LOS derived lipid A with its direct ligand that serves as an intermediary structure to activate and permit signaling of toll-like receptor (TLR)4. In Project 2 (Robin Ingalls, MD, PL), we will determine if naturally occurring mutations in gonococcal LOS or polymorphisms in the TLR4 adaptor Mai, account for differences in the host inflammatory response to infection. In Project 3 (Caroline A Genco, PhD, PL), we will examine the role that TLRs and cytosolic nucleotide oligomerization domain (NOD) protein receptors (NOD-like receptors [NLRs]) play as receptors for Neisseria ligands. In Project 4 (Sanjay Ram, MD, PL), we will examine novel roles for the alternative complement pathway (ACP) enhancing molecule. Properdin, in blocking TLR4 mediated signaling by LOS and separately, in amplifying potentially protective vaccine induced antibody function. In Project 5 (Peter A. Rice, MD), we will examine peptide mimics of gonococcal LOS as potential vaccine candidates in a humanized mouse model of gonococcal infection while also determining if natural antibodies against the candidates protect exposed women from gonococcal infection. The Center will have five Cores (Clinical, Laboratory, Animal Statistical, and administrative) providing support to 4 or 5 of the 5 Projects.